Injection apparatus



March 15, 1955 JENSEN 2,704,073

INJECTION APPARATUS Filed Sept. 21, 1953 United States Patent INJECTION APPARATUS Erik Jensen, Copenhagen-Vanlose, Denmark, assignor to Novo Terapeutisk Laboratorium A/S, Copenhagen, Denmark, a limited liability company of Denmark Application September 21, 1953, Serial No. 381,418

Claims priority, application Denmark September 24, 1952 8 Claims. (Cl. 128-218) The present invention relates to an injection apparatus in the form of a so-called hypodermic syringe, adapted for use by non-experts in administering injection of medicaments or serum in their own bodies, whereby the whole dose contained in the syringe is emptied in one m ectlon.

Hypodermic syringes are known in which the hypodermic needle before use is contained within the sterilely sealed cylinder or casing of the syringe and 1s moved forward when being used by pushing into the casing a piston disposed at the rear end thereof, whereby the point of the needle perforates a cover at the front end of the casing. This kind of hypodermic syringe suffers from the drawback that the injection of the contents of the syringe starts simultaneously with the piercing of the cover by the needle point. If flie syringe is completely filled with medicament, some of it will be lost or not properly utilized. If the syringe contains air in addition to the medicament, the air will have to escape through the needle before the injection is effected, and this may be accomplished simultaneously with the initial movement of the needle. Such a partially filled syringe should not, however, be entrusted to persons not skilled in the use thereof.

The main object of the invention is to avoid these drawbacks.

Another object is to provide an apparatus of the kind in question in which the injection of the medicament or serum is withheld until the point of the needle has penetrated the tissue to a certain distance under the skin.

A further object is to ensure that nothing whatever of the contents of the syringe escapes through the needle while the latter is being projected to a certain dlstanc under the skin. When the needle has reached this position the injection must begin and during the in ection the point of the needle must move deeper and deeper mto the tissue.

Finally, a still further object is to provide an apparatus of a cheap and reliable construction adapted for rough use.

With the above and other objects in view the present invention consists in the combination and arrangement of parts, hereinafter more fully described, illustrated in the accompanying drawings and more specifically pomted out in the claims, it being understood that changes may be made in the form, size, proportions, and details of construction without departing from, or sacrificing any of the advantages of the invention.

the drawings Figs. 1, 2 and 3 are shown axial sections of three different apparatuses embodying the invention.

In the embodiment shown in Fig. 1 the casing of the apparatus consists of a cylindrical tube of glass or plastic, having at one of its ends an outwardly pro ecting collar 12 which serves as a means for attaching a cover 14 of resilient material, e. g. rubber, a metal ring 16 being pressed around said cover, whereby this end of the casing 10 is hermetically sealed. In the rear end portion of the casing there is inserted a stopper or piston 18 of elastic material, e. g. rubber, the circumference of which is provided with circumferential tightening members in the form of ribs 20, which fit hermetically tight to the internal face of the casing. Longitudinally, preferably coaxially, within the piston 18 there is provided a passage 22, in which a tight-fitting rod 24 is slidably mounted. The forward end of this rod serves as a holding member for a tubular injection needle 26, which at its forward end is beveled, and the inlet aperture of which is formed by a 2,704,073 Patented Mar. 15, 1955 hole 28, provided at the end of the rod 24 to which the needle is secured, and communicating with the channel in the needle at the rearmost end thereof. The rear end of the rod 24 has an enlargement 30 providing an abutment cooperating with the rear end of the piston 18 when the apparatus is in use. The enlargement 30 is smaller than the bore of the casing 10. To the rear of said enlargement is arranged a part 32, serving as a handle.

When the described apparatus, which, as it will appear, generally is constructed as a so-called hypodermic syringe is supplied from the manufacture, the parts assume the position shown in Fig. 1, which e. g. may be assured by means of a suitable surrounding packing. The internal space of the syringe is entirely filled with an injection fluid. As will be seen, the hypodermic needle 26 is completely enclosed in the sterilely sealed part of the syringe. When an injection is to be administered, the syringe is suitably so applied that the cover 14 rests against the skin and the syringe projects upwardly at right angles thereto. Pressure is now applied to the handle 32, whereby the rod 24 is displaced inwardly in the passage 22 in the piston 18. Simultaneously the pointed end of the needle 26 penetrates the cover 24 and will gradually be projected a distance therefrom, so far without any injection being effected, however, because the aperture 28 is still located within the passage 22 and thereby remains closed. At the moment when this aperture leaves the piston 18, the forward end surface of the enlargement 30 will abut against the rear end surface of the piston, and during the continued advancement of the rod the piston will be moved forwardly, and the contents of the syringe will be ejected. During the ejection the point of the needle will move deeper and deeper into the tissue, which has the special importance, if the needle should have hit a vein, that a trifle only of the contents of the syringe will be ejected into the vein. Furthermore, it is advantageous that the ejection does not start until the point of the needle is situated a certain distance under the skin. During the first part of the movement of the rod 24 the slight quantity of fluid contained in the forward part of the passage 22 will be expelled into the space of the easing 10, the only consequence thereof will be that the piston 18 is simultaneously moved slightly to the rear.

The embodiment shown in Fig. 2 differs from that of Fig. 1 only in different designs of the casing 10, the piston 18, and the rod 24. At its forward part the piston has a neck part 34. Corresponding thereto the forward part of the casing 10 is narrowed, so that the piston in its forward position can displace all the fluid from the space of the casing. Furthermore, the piston has a rearwardly extending skirt or collar 36, which carries the larger portion of the tightening ribs 20. The skirt 36 surrounds a recess 38 positioned to the rear of the neck part 34.

When during injection the piston is advanced, the movement is effected by the pressure exerted on the bottom of said recess by the abutment at the front end of the part 30. By this means it is obtained that the skirt 36 is exposed to traction during the advancement of the piston, whereby the friction against the casing 10 is reduced. The neck 34 has been introduced chiefly to obtain sufiicient length of the passage 22.

According to Fig. 3 the piston consists of a tubular body 40 of rigid material, e. g. a suitable plastic, in which a piston-shaped holding member 42 for the injection needle 26 is slidably disposed. The rear end of the needle is received in a slot 44 in the member 42, and immediately to the fore thereof there is disposed on the needle a small rubber disc 46, which is designed to prevent the injection from being effected, before the needle has penetrated to the desired depth. On a pin 50 at the rearward end of the member 42 there is provided a similar rubber disc 52, which is adapted to provide tightness behind the slidable member 42 during its movement within the passage 48 in the body 40.

The front end of the tubular body 40 is surrounded by a body 54 of elastic material, e. g. rubber, which provides tightness against the casing 10 of the syringe. For the advancement of the member 42 and consequently of the needle 26 there is provided a rod 56, which constitutes a separate part and thus does not form the holder for the needle, in contradistinction to the embodiments heretofore described. At its rearward end the rod 56 has a handle 58, which abuts against the rearward end of the body 40, when the member 42 is completely advanced in the passage 48, and thereby pushes the piston forward to expel the contents of the syringe.

Through the body 40 the pressure is transferred from the handle 58 to the forward part of the body 54, whereby the advancement of the piston is facilitated as mentioned in the foregoing.

The invention is not limited to the embodiments herein shown and described, which may be modified in several respects without departing from the spirit of the invention.

Having thus fully described my invention I claim as new and desire to secure by Letters Patent:

1. An injection apparatus comprising a tubular casing, a cover at the front end of said casing, a piston movable in said casing and provided with a longitudinal passage, a member fitting tightly in said passage and being displaceable therein, and a hollow needle secured at its rear end to said member and projecting with its front end towards said cover, the rear end of said member being adapted to be pushed forward by hand, whereby said member slides in said passage without imparting movement to said piston, and the front end of the needle penetrates said cover.

2. An injection apparatus according to claim 1, in which the hollow needle has an inlet so positioned relative to said displaceable member, that it is held closed, until said member approximately has reached the end of its displacement in said piston.

3. An injection apparatus according to claim 2, in which a rod is provided adapted to displace said mem ber in said passage in the piston, said rod being provided with an abutment which after a certain movement of the rod cooperates with said piston so that the latter and said needle are displaced simultaneously.

4. An injection apparatus according to claim 1, in

which said piston consists wholly of elastic material and 4 comprises a neck part in which said passage is provided, and a'rearwardly extending collar cooperating tightly with said casing and enclosing a recess arranged behind said neck part, the bottom face of said recess being adapted to be acted upon for imparting movement to said piston.

5. An injection apparatus according to claim 1, in which said piston consists of a body of rigid material in which said member is displaceable, and of a body of elastic material enclosing the front end of said first named body, the rearward end of the latter being adapted to be acted upon for imparting movement to said piston.

6. An injection apparatus consisting of a syringe comprising a piston and a hypodermic needle carried by said piston, in which said piston comprises a front part to which said needle is connected and a rearwardly extending skirt formed with circumferential tightening members, means being provided for displacing said piston by exerting a pressure only at the rear face of its front part thereby exposing said skirt to tensile strain.

7. In an injection apparatus, a tubular casing, a cover at the front end of said casing, a piston movable in said casing and provided with a longitudinal passage, a hypodermic needle arranged displaceably in said passage and having an inlet at its rear end located in said passage:

closed by said piston, the front end of said needle being inside said casing adjacent to said cover, and means for displacing said needle relative to said piston to penetrate said cover before said inlet is uncovered by said piston.

8. In an injection apparatus according to claim 7, in which said piston consists of a body of elastic material in which is inserted a tubular body of rigid material for guiding the needle.

Tydings et al. Nov. 29, 1949 Smith Jan. 17, 1950 

